Letter | Published:

Calculation of Valence State Energies from Thermochemical Data

Naturevolume 199page591 (1963) | Download Citation



THE predictive power inherent in the concept of intrinsic bond energies has led to many attempts to calculate the energy of the hypothetical valence state of an atom in a molecule1–7. The intrinsic bond energy I can be defined1 by the equation: where ΔHf is the atomic heat of formation of a molecule, V is the energy of the valence state of an atom, and the summation is over all atoms and bonds in the molecule. The valence state of an atom in a molecule can be defined as the hypothetical state in which the free atom would find itself if the bond involved were broken without any change in the electronic configuration of the atom. Long has summarized the attempt to calculate the valence state energy of the tetrahedral carbon atom from thermochemical data1. He concluded that the probable limits for the energy of this state are approximately 60–70 kcal/mole. This value is quoted6 as the only experimental value presently available for this quantity. (In several communications with people in this field it has been brought to our attention that this number is still widely quoted.)

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  1. Laboratories Division, Aerospace Corporation, El Segundo, California



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